Various types of hydraulic couplers have been produced for use in hydraulic lines and constructed so that, when the coupler is disconnected, the uncoupled ends of the lines are sealed to prevent the escape of fluid. Valve means are provided to close the ends of the coupled hose. Means are provided for opening these valves when the parts of the coupler are reconnected so that fluid under pressure may again flow through the coupling from one line to the other line.
One of the problems experienced with couplers of this type lies in the fact that the two parts of the coupler are usually difficult to connect and to disconnect so that when the coupled lines are subject to high pressure, it is extremely difficult either to disconnect them or to reconnect them. Couplers of the type in question usually include a male portion which is detachably inserted into a female portion. The female portion may be provided with a series of angularly spaced radially extending holes which accommodate steel balls. In connected position of the two portions, these balls extend into a peripheral groove encircling the male portion. A slidable sleeve is resiliently urged into position to urge these balls inwardly, and to hold these balls from outward movement, and thus to maintain the balls engaged in the groove. The slidable sleeve normally includes an internal peripheral groove at one end thereof so that when the slidable sleeve is moved into disconnect position, the balls may be forced outwardly into the internal groove to permit the two parts or portions of the coupling to be disconnected. The peripheral groove in the male portion of the coupling is provided with a tapered wall so that when the balls are not held from outward movement by the slidable sleeve, a wall at one side of the groove will act as a cam to force the balls outwardly and to permit release of the male portion of the coupler from the female portion thereof.
The problem which has been experienced with couplers of this type lies in the fact that the holes in the female portion of the coupler in which the balls are located are normally formed on an axis normal to the axis of the coupler. As a result, when the coupler is under high hydraulic pressure, the tapered wall of the groove in the male portion of the coupler urges the balls outwardly against the inner cylindrical surface of the slidable sleeve or collar with such force that it may be impossible to manually slide the collar into disconnect position. Normally there is pressure tending to disconnect the two portions of the coupler. When the pressure tending to disconnect the coupling is high, the camming force of the wall of the groove in the male portion exerts sufficient force against the balls so that the slidable collar cannot be moved by hand. As an example, it has been found that a common type of commercial coupler, when placed in a one-half inch inside diameter fluid line, cannot be manually disconnected by most persons where the pressure in the line exceeds 500 lbs. If the hydraulic line is subjected to a higher pressure, the force exerted against the disconnect collar which is frictionally engaged by the balls is sufficient to lock the collar from manual slidable movement into disconnect position.
A further difficulty with couplers of this type lies in the fact that when the two parts or portions of the coupler are reconnected, it is difficult to telescope the male and female parts into interlocked position due to the fact that the valve means closing the ends of the two lines must be forced into an open position as the parts of the coupler are connected. If the parts of the line are under high pressure, the valve means closing the ends of the two coupler portions are urged into closing position with such force that it is difficult or impossible to manually reconnect the parts of the coupler.